Liquid applicator



INVENTORS ROBERT?A Li BUCKINGHAM NITFORNEYy NOV 24, 1964 N. J. BLAzENsKY, JR.. ETAL 3,158,030

LIQUID APPLICATOR 3 Sheets-Shea?l 2 Filed Deo. 27. 1960 FIG. 3

NOV- 24, 1964 N. J. BLAzENsKY, JR., ETAL 3,158,080

LIQUID APPLICATOR File Dec. 27. 1960 5 Sheets-Sheet 'S 2 PRESSURE (lbs/in) ,o

FIG. 5 0 5&0 15o Io 20o FLOW (cc/min) M GAP vs Q VOL/REV. IO- Based oni Inch cnnulus VOLGENERATEDICCI 8 REVOLUTION I I I 02468101214161820 GAP (.OOI Inch) 90 RP. M. vs GAP 8O Based onzIOO cc/mn flow 70 REPLACEMENT FACTOR I REM. 60

I I I I l I I I I 0124 68101214 161820 FIG. 7 GAPIOOI inch) United States Patent O bury, Conn., N217., assignors to 9 @Co New The present invention relates to a device for coating a surface, and more particularly to a device for uniformly applying a minimal amount of filtered lluid to uniformly coat a surface.

In the development of a photographic emulsion which is capable of resolution in the neighborhood of 1G03 lines per mm., it is essential that the developing i'luids be free of impurities since a very minute impurity particle may be capable of obliterating a significant portion of the image. Developer and hypo (sodium thiosulfate) crystals in particular cause specks to form on the emulsion which impair the image quality. lt is therefore necessary to expose and develop `such a film in a dust free atmosphere and, in addition, to use only iiltered r'luids for the various steps of the process to prevent contam'mation of the emulsion by impurities in the lluids themselves.

ln the development of high resolution iilms, the volume of each of the solutions use` should be kept to a minimum, consistent with the satisfactory processing, since the number of foreign particles to which the emulsion is subjected is proportional to the volume of solution which is dispersed on the emulsion.

The use of a ltered fluid is well known in the art. The use of rneniscus applicators for supplying fluids to a lilin during development also is Well known. However, the known meniscus type applicators utilizing an elongated meniscus tend to separate into two or more individual meniscuses when a `lilm is moved in contact with the meniscus. The conventional type meniscus applicator may function satisfactorily if a copious tlow of fluid is not undesirable. However, where it is desire-d to have a minimum ilow of lluids, the elongated type meniscus is unsatisfactory.

As used herein, a meniscus is defined as the body of lluid formed on the upper applicator surface when liquid is supplied to that surface. This body of fluid (meniscus) is distinguished from the fluid absorbed in the wick or sponge of the type of applicator commonly used to meisten glue such as on stamps and envelope laps or the liquid overflowing freely from the top of a vertical pipe. rthis meniscus, when not in contact with a moving surta e to be coated, forms a stable body of liquid.

Due to the surface tension, liquids tend to assume a spherical shape. When nim is moved transversely to and is in contact with the conventional elongated meniscus, the liquid adheres to the moving film. rlhere is a tendency, due to the cohesive forces of the liquid, for the entire meniscus rather than merely the surface portions to move with the film. rtendency of the meniscus to follow the film results in the meniscus breaking at one or nore points and, due to cohesive action, the several individual meniscuses tend to form into spherical shapes and thus leave intervening spaces on the nlm which are not coated with the liquid. The present meniscus applicator is designed to take advantage of the natural tendency ogt a liquid to `assume a spherical shape.

Accordingly, a primary object of this invention is to provide filtered fluids for the processing of high resolution film.

Another object of this invention is to provide lluids which are iiltered immediately prior to being applied to the i'ilm.

A further object of this invention is to provide fluid in the form of a mcniscus in contact with which the film is moved to obtain uniform coating.

Yet another object of this invention is to provide a circular type meniscus applicator' to present a circular meniscus which will not be broken by the movement of film in contact therewith.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.

In the drawings:

FIGURE l is a sectional elevation taken along the line l-l in FIGURE 2.

FIGURE 2 is a plan view of the apparatus shown in FEGURE l.

FIGURE 3 is an enlarged sectional view of the meniscus head.

FIGURE 4 is a plan View of the meniscus head. FGURE 5 is a graph of applied pressure versus liquid flow.

FGURE 6 is a graph of volume of luid per revolution versus gap.

FlGURE 7 is a graph of rpm. versus gap.

ln accordance with the concept of contamination free development of photographic lm, a photographic disc processor is housed in a stainless steel cabinet (not shown). A top cover is provided as a dust seal and the cabinet is internally pressurized to keep dust out. The necessary solutions for processing are enclosed within the steel cabinet in polyethylene containers on an indexable turntable, and are successively moved to a dispensing station for presentation to the emulsion. Fluid containers are constructed of chemically inert polyethylene materials and after a single use, are discarded. A separate applicator head for each bottle is constructed of chemically inert material such as cucite. The applicator head assembly serves as a bottle cap for sealing against pressure leaks, as a support for the fluid container, as a support for a iilter, `and as an adiusting mechanism for locating the top of the applicator head with respect to the photographic emulsion. Each fluid is iiltered immediately prior to its presentation to the photographic emulv sion. The various fluids are presented to the photographic emulsion on a continuous replacement basis with the expired solution being replaced continually by pressurized solution which is discarded after a single use.

The complete processing of a high resolution emulsion may include the following steps.

(l) Pre-wash. Pre-washing with a solution which may be for example Eastman Kodak Photo-flow, insures uniform f'etting with the developer in a subsequent step.

(2) Developer. An appropriate developing solution, for example Eastman Kodak D-19, is applied to develop the photographic image.

(3) Stop bath. The stop bath, for example Eastman Kodak Glacial Aletic Acid, neutralizes the developer, stopping the developing process and dissolving or retarding the formation of calcium scum.

(4) Fixing. The fixing bath, for example Eastman Kodak Rapid Fixer, dissolves the light-sensitive silver haloid, stops developing, and forms complexes which are stable upon dilution so that they will not decompose during washing and thus cause stains.

(5) .Hypo clearing rinse. Certain washing aids can be used to make possible more rapid and complete washing after fixing. For example, a 3G second rinse in a 2 percent solution of sodium sulfate may be used.

(6) Washing. The emulsion is washed with distilled water to remove all soluble compounds, in particular, the fixing salts which are contaminated with dissolved silver areaoso compounds in the form of complexes with thiosulfate. Efective Washing is especially important where ph tographs are to bc lrept as archival records.

(7) Pre-drying. Washing and drying are the most critical operations for the preserving of cleanliness and the shorter these times can be, the less the likelihood of contamination. A thirty second bath in ethyl alcohol, after washing, produces a dry disc in approximately 7 minutes, thus reducing the duration of the critical tacky stage between washing and drying when contamination from the atmosphere is most lilrely.

(8) Drying. A linal drying time of l() minutes during which the disc is rotated at 300 rpm. insures a completely dry emulsion and terminates the disc processing cycle.

Referring to FGURES l and 2, a turntable l@ on a hub l2 is rotatably mounted on a rotatable table i3 and is adapted to receive eight individual iluid containers lift-.l through tl-8. Actually, only seven are used and the eight position is used for loading. The turnable lll is indexable to present the containers successively to a dispensing station lf, FlG. 2. A bearing permits rotation of the hub lZ around a shaft which is a stationary support and conduit.

A glass disc itl having a photographic emulsion on the lower side is rotatably mounted on a shaft which may be raised and lowered in a bearing Z3 to the positions 22E-l and 212-2, shown in 3, by means of an air piston (not shown).

A hypodcrinic type needle is mounted on a hollow plunger 26 of a double acting gas operated cylinder 23 and may be moved selec ively between the positions Sil-l and 3h42., whereby the needle may be withdrawn from one polyethylene container' ld and inserted through the sidewall of the next container ld which io indexed to the dispensing station Air pressure for operating the cylinder 23 is supplied selectively through tubes and 3st.

Flhe essurizing for a conta r lf3?, for example nitrogen, is supplied to the needle 2e througa the tube 35 and hollow plunger e penetratable wall ot the containers ld allows piercing by the needle 24 and is strong enough to withstand the pressure necessary to cause liow of the solutions. The polyethylene containers are i4 ert to the chemicals used in the developing process.

Prior to the indexing of the turntable to present a new container 'le to the dispensing station i6, the disc 5.8 is raised trom the position .Z2-2 to the position 21E-l by raising the shaft Teil in the bearing 23. After the new container ld is indexed to the dispensing station, the disc l is again lowered to the position 212-2. When pressure is applied through the needle 2d to the fluid 33, the lluid is forced through a lead tube il@ and a porous filter element to form a meniscus ld on the upper surface of the applicator head which is generally designated d5. The internal pressure in the container is adjusted to provide the minimal liow of lluid through the filter 42 for complete coating of the portion of the disc which is spanned by the applicator head Referring to FiGURES 3 and 4, an enlarged sectional view of the head is shown as well as a partial plan View. rlhe portion of the emulsion on the disc l which is to be developed is donned approximately by the outer edge 4? of the disc lll and the dotted line 5i). The annulus deiined by the lines 4S and varies depending upon which solution is being supplied, since all heads i5 are not of the same diameter.

Cleanliness of solutions coming in contact with the emulsion is of great importance. Satisfactory optical delineation of information marks on the disc requires that no more than l percent of an information mark be obscured by foreign material or other defects. Where the smallest marli on the film is of 3.35 X10-4 inches wide by 3.3l lG-4 inches, and thus ll.l ltl8 sq. inches in area, the equivalent circular area representing l0 percent of the smallest mark has a diameter of l.l9 hlm'l inches,

or approximately 3 microns. illus a iilter retention of particles 3 microns in diamo er would just satisfy the l0 percent tolerance.

T he lilter Ai2 located in the applicator head is a Solas Micro-Porous Porcelain Bise No. @l which retains particles 2 microns in diameter. rlhe iilter is 3'() mm. in diameter by 31g inch thick with a lAXl/l inch step machined around the uper edge to allow llush location of the filter with the upper surface of the applicator head as well as to retain the ilter.

Applicator Hear! rlhe lead tube is lined in a core section and cornes flush with the upper surface 50i of the section A ring section 56 contains an annulus S3 complementary to the machined step in the litter element in assembling the applicator head, the filter element is placed in the ring section do where the top surface ol the filter element comes ilush with the top of the ring. The mcnlscus will be formed on the surface formed on top ot the ring Si and the iilter element An (E1-ring ed, for example neoprene, is placed against the bottom side of the lter element and is followed by the core section which is screwed in by threads 62. A second C-ring dit is inserted in a central aperture of the core section 52, followed by the container lid which is screwed into place by threads 6d. A locking ring E is threaded onto the outer t,or-tion ofthe ring by threads into an opening 7d in the turntable by thread "I and is held in place by a set screw 7 ring 72 con a channel 79 formed complementary to two lugs i which are 180 degrees apart on the ring section e openings (not shown) which are located 180 degrees apart in an annulus S2 forming the lower side of the channel 79 in the ring 72 permit insertion of the assembled applicator head into the ring followed by a quarter turn of the head assembly. rThe head assembly is locke into place by screwing the locking ring 6? up against tt e lower side of the ring 72. By means of the threads 7&5, each ring 72 may be adjusted individually to provide proper spacing between the head assembly and the emulsion.

Each of the several heads is positioned so the outer edge coincides with the outer edge of the disc l. 'Ehe diameter of the pre-wash and developer heads is l./l-95 inches; the diameter of the stop bath and iixer heads is 1.515 inches; the diameter of the hypo clearing rinse, final wash heads is 1.615 inches; and the dialnet of alcohol head is 1.645 inches. The overlap of dispensing head areas insures adequate processing in the boundary area between the process and the unprocessed emulu on.

The actual volume of cach fluid to be used is determined by the rate ol flow or" the solution and the duration of ilow. The disc lil may be rotated from G to 300 rpm. by means of a DC. shunt motor and variable power supply (not shown). The resultant tlow of iluids from the containers M is directly proportional to the pressure applied to the solution inside the bottle as shown in the graph of EEGURE 5.

FIGURE 6 shows the relationship of the gap between the head d5 and the disc l versus the volume per revolution, based on a 1%. inch diameter dispensing head. lxperirnental results show that a high resolution emulsion plate held horizontally holds a layer of tap water .0045 inch thick on its underside. However, a gap of this dimension is too critical to maintain. PGURE, 7 shows the relationship between disc speed and gap.

Experience has shown that a gap in the order of .014 inch produces a stable rneniscus contact with the disc. Thus, for a flow rate of 1GO cc. per minute and a replacement factor of l, a .014 inch gap requires l0 rpm. for the disc.

While the invention has been particularly shown and described with reference to a preferred embodiment there- 5 of, it will be understood` by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. In apparatus for applying a coating liquid to a surface by moving said surface past an applicator with a space between said surface and said applicator but with said surface in contact with a coating liquid supplied from said applicator,

an applicator having a horizontal circular upper surface to which said liquid is supplied, and

means for supplying said liquid to said upper surface sufiicient to ll said space with a circular meniscus of said liquid forming a stable body having a flattened oval cross-section and to replenish the liquid which is carried away on the coated surface so there is no excess ow from the applicator.

2. In apparatus for applying a coating liquid to a surface by moving said surface past an applicator with a space between said surface and said applicator but with said surface in contact with a coating liquid supplied from said applicator, f

an applicator having a horizontal substantially circular upper surface to which said liquid is supplied, and

nieans for supplying said liquid to said upper surface suiiicient to iill said space with a substantially circular meniscus of said liquid forming a stable body having a flattened oval cross`section and to replenish the liquid which is carried away on the coated surface so there is no excess flow from said applicator.

References Cited in the file of this patent UNITED STATES PATENTS Alwart Nov. 17, 1903 Zenner et al July 19, 1921 Rose Dec. 12, 1933 Jones Mar. 12, 1935 Rosebush Nov. 15, 1938 Rosebush Aug. l, 1939 Brightwell Oct. 3l, 1944 Luboshez Feb. 7, 1950 Wampole et al Apr. 10, 1951 Grimson June 3, 1952 

2. IN APPARATUS FOR APPLYING A COATING LIQUID TO A SURFACE BY MOVING SAID SURFACE PAST AN APPLICATOR WITH A SPACE BETWEEN SAID SURFACE AND SAID APPLICATOR BUT WITH SAID SURFACE IN CONTACT WITH A COATING LIQUID SUPPLIED FROM SAID APPLICATOR, AN APPLICATOR HAVING A HORIZONTAL SUBSTANTIALLY CIRCULAR UPPER SURFACE TO WHICH SAID LIQUID IS SUPPLIED, AND MEANS FOR SUPPLYING SAID LIQUID TO SAID UPPER SURFACE SUFFICIENT TO FILL SAID SPACE WITH A SUBSTANTIALLY CIRCULAR MENISCUS OF SAID LIQUID FORMING A STABLE BODY HAVING A FLATTENED OVAL CROSS-SECTION AND TO REPLENISH THE LIQUID WHICH IS CARRIED AWAY ON THE COATED SURFACE SO THERE IS NO EXCESS FLOW FROM SAID APPLICATOR. 